1. Technical Field
The present invention relates to a projector for displaying an image by projecting a light beam emitted from a light source device on a projected surface.
2. Related Art
A projector of a rear projection type that displays an image by scanning a screen (projected surface) with a laser beam has been proposed in the related art. In this projector, since complete black can be displayed by stopping supply of the laser beam, a high-contrast display is possible in comparison with, for example, a projector that employs a liquid crystal light valve. Since the laser beam is high in directivity, a projection optical system can be simplified. Therefore, the projector can be formed into a compact and simple structure. In addition, color display is achieved easily by combining a plurality of colors of laser beams such as red, green and blue, and since the laser beam is high in monochromaticity, the color display with high color purification is achieved.
As the projector of the rear projection type, a projection type laser image display device employing a red laser source, a green laser source, and a ultra-violet laser source is proposed (for example, see JP-A-7-67064). The projection type laser image display device disclosed in JP-A-7-67064, a fluorescent material is applied on a screen, and hence the laser beams emitted form the red laser source and the green laser source are dispersed on the screen surface. The laser beam emitted from the ultra-violet laser source is excited by the fluorescent material, which generates blue light. This blue light is diffused on the screen surface.
In the case in which the projector of the rear projection type as described above is employed, there is a problem such that dazzling, which is called “scintillation” or “speckle” may occur in the laser beam projected onto the screen. According to the projection type laser image display device disclosed in JP-A-7-67064, since the laser beam is diffused on the screen, occurrence of the dazzling cannot be resolved satisfactorily. When the screen is accidentally damaged by means of an unexpected cause, the laser beam may be irradiated directly toward the outside without being diffused. Therefore, the reliability of the entire device is not sufficient.